Scaling mobile app works fine on the X but not on the Y

I originally made my app to work for iphone only but I am now scaling it to work on Ipad/ Android etc. I am doing all the scaling manually. It is a tabbed application.

I am scaling all x and y locations and widths and heights by a scale factor that is created using..

          scaleFactorX = stage.width/320;

     scaleFactorY = stage.height/480;

It works perfectly on the x but not quite enough on the y as objects look a little squashed vertically.

I can't think why this is. If I were to alter the y scalefactor it would put things out when at the original phone size.

The only part I'm not scaling manually is the actionBar and the bottom tabs. They are currently using default skins which use the DPI classification to determined size. I have however overridden this and set the action bar to use a skin with a much greater layoutContentGroupHeight. This hasn't however had any effect on the y scaling of objects in the main display area.

The y scale isn't out by much, but it bothers me. If anyone has any suggestions I'd appreciate it.

Thanks.